At recent track event, noticed some play in rear wheel after typical 20 min session. Seemed to be bearing, since the rotor and wheel both wobbled about 1/8 inch at outside of tire. Noticed by shaking tire with hands at 6 and 12 position with rear jacked up. Oddly, the wobble goes away after everything cooled off. Do you think this is the bearing going bad or can something else loosen up with braking heat? Looseness only on one side.

Car is 996 GT2. Thanks.

 

I wouldn't be tracking a car that had that much wobble in a wheel. Are you sure it wasn't just that your lug nuts were tightening up when they cooled down, and were slightly loose when they were hot? There's only a couple of things that can cause wobble in those components at once which would be the bearing/hub or the wheel itself. Did you get under the car at all to see what the wobble looked like from the backside in terms of what was actually moving?

 

Most likely a bearing. Make sure the axle nut is tight... 350 ftbl...

 

The big axle nut and lug nuts were tight. The looseness did not appear until at the track and the brake rotor etc were really hot. In fact in non-track conditions their is no discernible play just from hand-shaking. That is the weird part. I have already decided to replace the bearing, but wondering if anything else might need attention. Thanks for the replies.

 

I've probably done about 20 of those bearings, seems to be more common the the GT2's that were early production, bearing changed from a hard rubber sheild in the first ones to a metal sheild on one side in the current replacement. i've noticed that on the rubber seal the bearing that were going bad had quite a bit of rust inside causing the failure. Pretty sure thats why they changed the design. Also to note is that some bearings looked perfect until they were taken apart, then wow Had a few even run true with a dial indicator, just the smallest "feel" of a drag spot, horrible inside tho.
I posted a nice DIY on this.....not to bad a job all in all...good luck !!

 

^^ DERBOOST has a great DIY post that I clipped and saved, for future reference...

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here is the spec. right in the middle of some mods and bearing change